CN110757028B - SMAW welding rod with low hygroscopicity - Google Patents

Abstract

The invention provides a SMAW welding rod with low hygroscopicity, which comprises a core wire and a coating. The coating comprises the following raw materials in parts by mass: 30-40 parts of marble, 10-15 parts of silicate, 10-20 parts of high-carbon ferrochrome, 5-10 parts of titanium dioxide, 5-10 parts of mixed rare earth and 10-20 parts of binder, wherein a polyvinyl alcohol (PVA) binder is adopted to replace the traditional sodium-potassium water glass as the binder in the binder manufacturing process. Compared with the prior art, the invention has stable components, better mechanical property on welding performance, good weld metal deposition and strong slagging capability. Compared with the common coated welding rod, the water content of the welding rod and the welded weld deposit metal after welding is far lower than that of the common coated welding rod. Can be widely used in welding environment with heavy water content. Moreover, the mechanical properties of the low moisture absorption electrode of the present invention can completely reach or even exceed those of the J50 electrode.

Description

SMAW welding rod with low hygroscopicity

Technical Field

The invention belongs to the technical field of welding, and relates to a SMAW welding rod with low hygroscopicity, which is widely applied to welding environments with heavier water content, such as marine environment welding engineering, bridge welding engineering and the like.

Background

Manual Arc Welding (SMAW), a commonly used industrial welding process, is convenient and quick, and can easily operate in different environments, often in environments with relatively high moisture. In the process of welding metal, because the coating is easy to be affected with damp, the technological performance of the welding rod after being affected with damp is deteriorated, hydrogen in water easily causes air holes and cracks to be generated on a welding line, the coating can be flaked off or greatly splashed in high-temperature welding, and a molten pool cannot be fully protected; moisture is gasified at high temperature, and oxygen of the moisture has chemical combination effect on carbon to reduce the strength of the material; hydrogen bonds with the material to increase brittleness, hydrogen cracks can form, or brittle white spots reduce material performance.

The welding rod consists of a coating and a welding core. The coating of the welding rod is decomposed and melted into stroke gas and slag in the welding process, the coating of the welding rod is the part which is most easily fused with water, in order to remove moisture, a drying procedure is generally added to the welding rod before welding, and the drying time and energy consumption obviously increase the welding cost. The coating of the welding rod is formed by combining mineral powder, metal powder, organic matters and chemicals. The action of each ingredient in the coating is different. A large amount of water glass which is a substance is added into the coating of the traditional welding rod to serve as a binder of the coating, and although the water glass which is a substance with better binding property can prevent the coating from falling off in the welding process, the water glass is a substance which has larger water content and is easy to absorb moisture.

Disclosure of Invention

The invention aims to provide a SMAW welding rod with low hygroscopicity, which adopts a polyvinyl alcohol (PVA) binder to replace the traditional sodium-potassium water glass as the binder and adopts a certain proportion and a stirring and uniformly mixing mode to achieve the characteristic that the coating of the welding rod has low hygroscopicity. The method can be widely applied to welding environments with heavier water content, such as marine environment welding engineering, bridge welding engineering and the like.

The specific technical scheme of the invention is as follows:

the invention provides a SMAW welding rod with low hygroscopicity, which comprises a core wire and a coating.

The coating comprises the following raw materials in parts by mass:

30-40 parts of marble, 10-15 parts of silicate, 10-20 parts of high-carbon ferrochrome, 5-10 parts of titanium dioxide, 5-10 parts of mixed rare earth and 10-20 parts of binder.

The mixed rare earth comprises the following raw materials in percentage by mass: 10-30% of yttrium oxide, 30-50% of cerium oxide and 20-40% of lanthanum oxide.

The binder comprises the following raw materials in parts by mass:

25 parts of hydroxypropyl methyl cellulose ether, 55 parts of polyvinyl alcohol (PVA), 4.5 parts of sodium silicate aqueous solution, 15 parts of latex powder and 0.5 part of hydrochloric acid;

the sodium silicate aqueous solution is prepared according to the mass ratio of sodium silicate to water of 1: 1.5.

The mass concentration of the hydrochloric acid is 10%.

The preparation method of the adhesive comprises the following steps:

25 parts of hydroxypropyl methyl cellulose ether, 55 parts of polyvinyl alcohol (PVA), 4.5 parts of sodium silicate aqueous solution and 15 parts of latex powder are mixed, 0.5 part of hydrochloric acid with the mass concentration of 10% is added after uniform mixing, the mixture is fully stirred for more than 4 hours, the temperature is kept at 40 ℃ after stirring, and the time is controlled to be more than 2 hours, so that the mixture is fully dissolved. Thus obtaining the binder.

The coating finished product of the welding rod is finally obtained by adding other components of the coating into the binder mixed by the proportion.

Specifically, the preparation method of the coating comprises the following steps:

uniformly stirring and mixing the marble, the silicate, the high-carbon ferrochrome, the titanium dioxide and the mixed rare earth according to the formula amount, and then adding the adhesive and uniformly stirring to prepare a welding rod coating;

further, the stirring temperature is controlled to be 20-30 ℃.

The alloy elements in the iron-based core wire are controlled to comprise the following components in percentage by mass:

less than or equal to 0.017 percent of C, 0.05-0.20 percent of Si, 0.60-1.20 percent of Mn22.4-25.06 percent of Cr, 2.0-5.0 percent of Mo2, 5-10 percent of V, 25-30 percent of Ni and the balance of Fe.

Preferably, the alloy elements in the iron-based core wire are controlled to comprise the following components in percentage by mass:

0.015% of C, 0.10% of Si, 1.00% of Mn, 24.00% of Cr, 4.0% of Mo, 8% of V, 30% of Ni, Fe: and (4) the balance.

The invention designs the components in the mixed rare earth, adopts polyvinyl alcohol (PVA) binder to replace sodium-potassium water glass in the traditional process in the process of manufacturing the binder, adopts the PVA to replace the sodium-potassium water glass as one of the components of the binder, can directly reduce the water content of the binder from the source, and avoids the use of the PVA to possibly reduce the binding degree of the binder, so a certain amount of latex powder is added to increase the viscosity in the basic increment, and sodium silicate aqueous solution is adopted to replace the added water in the traditional process, thereby further controlling the water content of the binder. The added hydroxypropyl methyl cellulose ether not only further stabilizes the viscosity, ensures good fluidity, controls the water retention rate to enable the hydroxypropyl methyl cellulose ether to be quickly solidified, and reduces the cracks and the shrinkage which may occur when the viscous material is solidified. After the mixed and proportioned binder is mixed, the solid-liquid two phases are fully dissolved by stirring for 4 hours because the binder has the characteristics of solid-liquid two phases in the proportioning, so that the fusion on particles is achieved, and the phenomena of bubbles, holes, slag inclusion and the like in the binder are avoided. And the temperature is kept at 40 ℃ for 2 hours after stirring, so that the phenomena of insufficient dissolution and solid phase sinking caused by inconsistent temperature change on the surface and the inside of the adhesive in a dissolving and curing state of the adhesive are avoided.

Compared with the prior art, the SMAW welding rod with low hygroscopicity has stable components, better mechanical property on welding performance, good weld metal deposition and strong slagging capacity. By measuring the water content of the welding rod and the water content of the weld deposit metal after welding, compared with the common coated welding rod, the water content of the welding rod and the water content of the weld deposit metal after welding are far lower than that of the common coated welding rod. The method can be widely applied to welding environments with heavier water content, such as marine environment welding engineering, bridge welding engineering and the like. Moreover, the mechanical property of the welding rod with low hygroscopicity can completely reach or even exceed that of the common J50 welding rod.

Drawings

FIG. 1 is a macrostructure of a weld zone for a welding operation using a low moisture absorption SMAW electrode of the present invention;

FIG. 2 is a macrostructure of the junction of the parent metal region and the weld region of a welding operation using the low moisture absorption SMAW electrode of the present invention.

Detailed Description

Example 1

A SMAW welding rod with low hygroscopicity is composed of core wire and coating.

The coating comprises the following raw materials in parts by mass: see table 1 below.

TABLE 1 composition of the skins (parts by weight)

Marble, method for producing the same and marble plate	Silicate salt	High carbon ferrochrome	Titanium white powder	Mixed rare earth	Binder
						35	15	15	8	8	15

The mixed rare earth is prepared from the following components in percentage by mass:

the composition proportion of 25 percent of yttrium oxide, 45 percent of cerium oxide and 30 percent of lanthanum oxide is adopted;

the binder comprises the following components in parts by mass:

25 parts of hydroxypropyl methyl cellulose ether, 55 parts of polyvinyl alcohol (PVA), 4.5 parts of sodium silicate aqueous solution (the mass ratio of sodium silicate to water is controlled to be 1:1.5), 15 parts of latex powder and 0.5 part of hydrochloric acid;

the preparation method of the adhesive comprises the following steps:

mixing 25 parts of hydroxypropyl methyl cellulose ether, 55 parts of polyvinyl alcohol (PVA), 4.5 parts of sodium silicate aqueous solution (the mass ratio of sodium silicate to water is controlled to be 1:1.5) and 15 parts of latex powder, uniformly mixing, adding 0.5 part of hydrochloric acid with the mass concentration of 10%, fully stirring for more than 4 hours, keeping the temperature of 40 ℃ after stirring, and controlling the time to be more than 2 hours to obtain the binder.

The marble, the silicate, the high-carbon ferrochrome, the titanium pigment and the misch metal with the formula amount are uniformly mixed by a vertical mixer to prepare solid components, then the proportioned adhesive is added to be uniformly stirred to prepare the coating of the welding rod, and the stirring temperature is controlled to be 20-30 ℃.

The welding core comprises the following raw materials in parts by mass: see table 2 below.

Table 2 main components of the core wires%

C	Si	Mn	Cr	Mo	V	Ni	Fe
								0.015	0.10	1.00	24.00	4.0	8	30	The rest(s)

The moisture absorption rate (water content) of the welding rod under the same environment is measured by a Karl-Fischer potentiometric titration method (volumetric method) by selecting the welding rod of the invention with the same specification and a J50 welding rod of a common welding structural part. After the same specimens were welded using the same welding process parameters (welding pattern: Q345B plate material; welding angle: vertical welding; current: 50A; welding voltage 20V; welding speed 5 mm/s; pass: double-sided welding and double-sided molding), the weld metal was measured for diffusible hydrogen by the "tapping method", and the results are shown in tables 3 and 4.

TABLE 3 moisture absorption (water content) result data of electrode

TABLE 4 weld metal diffusible hydrogen results data (3 samples selected each)

The comparison shows that the SMAW welding rod with low hygroscopicity has stable components, better mechanical property on welding performance, good weld metal deposition and strong slagging capacity.

As can be seen from the macroscopic structures of the welding seam areas in the figures 1 and 2, the metal structures of the welding seam areas of the welding operation performed by the welding rod are stably fused, and the defects of hydrogen embrittlement, holes and the like do not occur. 3 samples were selected and the weld strengths after welding are shown in table 5.

TABLE 5 weld mechanical Properties comparison

Through the measurement and comparison of the water content of the welding rod, the moisture absorption rate of the SMAW welding rod with low hygroscopicity is far smaller than that of a common welding rod in different environments. Through the determination of diffusible hydrogen of weld deposit metal after butt welding, the water content of the weld deposit metal after welding of the SMAW welding rod with low hygroscopicity is far lower than that of a common welding rod. The welding seam strength comparison data after welding shows that the mechanical property of the welding seam of the low-hygroscopicity welding rod can completely reach or even exceed that of the common J50 welding rod.

Claims (4)

1. A SMAW welding rod with low hygroscopicity comprises a core wire and a coating, and is characterized in that the coating comprises the following raw materials in parts by mass: 30-40 parts of marble, 10-15 parts of silicate, 10-20 parts of high-carbon ferrochrome, 5-10 parts of titanium dioxide, 5-10 parts of mixed rare earth and 10-20 parts of binder;

the binder comprises the following raw materials in parts by mass:

25 parts of hydroxypropyl methyl cellulose ether, 55 parts of polyvinyl alcohol, 4.5 parts of sodium silicate aqueous solution, 15 parts of latex powder and 0.5 part of hydrochloric acid;

the preparation method of the adhesive comprises the following steps: mixing 25 parts of hydroxypropyl methyl cellulose ether, 55 parts of polyvinyl alcohol, 4.5 parts of sodium silicate aqueous solution and 15 parts of latex powder, adding 0.5 part of hydrochloric acid with the mass concentration of 10% after uniformly mixing, fully stirring for more than 4 hours, keeping the temperature at 40 ℃ after stirring, and controlling the time to be more than 2 hours to obtain the binder;

the stirring temperature is controlled to be 20-30 ℃;

the sodium silicate aqueous solution is prepared according to the mass ratio of sodium silicate to water of 1: 1.5;

the mass concentration of the hydrochloric acid is 10%.

2. The low moisture absorption SMAW electrode of claim 1, wherein said misch metal comprises the following materials in mass percent: 10-30% of yttrium oxide, 30-50% of cerium oxide and 20-40% of lanthanum oxide.

3. The low moisture absorption SMAW electrode of claim 1, wherein the sheath is prepared by: the marble, the silicate, the high-carbon ferrochrome, the titanium pigment and the mischmetal in the formula amount are stirred and mixed evenly, and then the adhesive is added and stirred evenly to prepare the coating of the welding rod.

4. The low moisture absorption SMAW electrode of claim 1, wherein the core wire comprises the following composition in mass percent:

less than or equal to 0.017 percent of C, 0.05-0.20 percent of Si, 0.60-1.20 percent of Mn22.4-25.06 percent of Cr, 2.0-5.0 percent of Mo2, 5-10 percent of V, 25-30 percent of Ni and the balance of Fe.

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